From the sphinx-maven plugin documentation :

The sphinx-maven-plugin looks for .rst files in the folder structure provided as part of plugin configuration within your pom file.

The plugin is not used to convert javadoc with Sphinx, but to add Sphinx-like external documentation to a Java project.

The only project I could find to achieve javadoc -> Sphinx is javasphinx however it is not maintained anymore.

*SAD TROMBONE*.

Oh well, let's just make sure the JavaDoc can be built locally upon a dedicated make something invocation (or whatever).
Once we have that, we can instruct sphinx to run maven, and then ship the javadoc-generated doc as static assets that sphinx will just ship somewhere under docs.s.o.

What was tried so far:

1. Using Sphinx html_static_path. Problem: it cannot copy the whole folder as is, and only outputs the content of the javadoc folder in _static.
2. Using Sphinx html_extra_path. Problem: same as above, expect now it is scattered in the root build directory.
3. Using Sphinx extension rawfiles. Problem: cannot control where the folder is copied (it defaults to the swh-graph/docs folder...).

The asset generation inside swh-graph is easy to add, however moving the generated javadoc folder to the right Sphinx location without simply adding a cp command in the swh-docs Makefile seems a bit complicated with current setup. We need a generic way of adding files/folder in the swh-docs build directory, I'll try to investigate on how to implement this in the next few days.